The science of hot air rising - Home Energy Pros2015-03-31T22:18:49Zhttp://homeenergypros.lbl.gov/forum/topics/the-science-of-hot-air-rising?xg_source=activity&id=6069565%3ATopic%3A68805&feed=yes&xn_auth=noBud,
I'm even more disappoint…tag:homeenergypros.lbl.gov,2012-09-26:6069565:Comment:949952012-09-26T22:37:53.962ZRobert Riversonghttp://homeenergypros.lbl.gov/profile/RobertRiversong
<p>Bud,</p>
<p>I'm even more disappointed in your obsessive compulsion to declare anyone "wrong" who sees a different perspective or a broader picture than you're capable of.</p>
<p>And you have no right to ask me or anyone else not to participate in any public discussion here.</p>
<p>If you start another thread to propagate this falsehood and slander, I will continue to counter it, as intellectual honesty requires.</p>
<p></p>
<p></p>
<p>Bud,</p>
<p>I'm even more disappointed in your obsessive compulsion to declare anyone "wrong" who sees a different perspective or a broader picture than you're capable of.</p>
<p>And you have no right to ask me or anyone else not to participate in any public discussion here.</p>
<p>If you start another thread to propagate this falsehood and slander, I will continue to counter it, as intellectual honesty requires.</p>
<p></p>
<p></p> I'm not going to fight back. …tag:homeenergypros.lbl.gov,2012-09-26:6069565:Comment:950922012-09-26T22:25:57.374ZBud Pollhttp://homeenergypros.lbl.gov/profile/EverettPoll
<p>I'm not going to fight back. I think you have demonstrated your objection sufficiently and any more would border on stalking. I will start another thread to continue my discussion and despite your declaration that you will continue until I give up, I hope you don't follow. I am disappointed in your obsessive lecturing and name calling and will let others judge your actions. Please stop.</p>
<p>Bud</p>
<p>I'm not going to fight back. I think you have demonstrated your objection sufficiently and any more would border on stalking. I will start another thread to continue my discussion and despite your declaration that you will continue until I give up, I hope you don't follow. I am disappointed in your obsessive lecturing and name calling and will let others judge your actions. Please stop.</p>
<p>Bud</p> I'll be done when you admit t…tag:homeenergypros.lbl.gov,2012-09-26:6069565:Comment:948882012-09-26T22:07:41.653ZRobert Riversonghttp://homeenergypros.lbl.gov/profile/RobertRiversong
<p>I'll be done when you admit that you're wrong in accusing everyone else of being wrong.</p>
<p></p>
<p>But I'm not holding my breath. On this issue, you are coming across as someone with a newly-discovered faith who is determined to convert the rest of the world over to it.</p>
<p>I'm glad that your epiphany helped you understand the stack effect, but you've stumbled upon one path to understanding and are insisting that it's the ONE AND ONLY TRUE PATH.</p>
<p>I'll be done when you admit that you're wrong in accusing everyone else of being wrong.</p>
<p></p>
<p>But I'm not holding my breath. On this issue, you are coming across as someone with a newly-discovered faith who is determined to convert the rest of the world over to it.</p>
<p>I'm glad that your epiphany helped you understand the stack effect, but you've stumbled upon one path to understanding and are insisting that it's the ONE AND ONLY TRUE PATH.</p> Let me know when you are done…tag:homeenergypros.lbl.gov,2012-09-26:6069565:Comment:951882012-09-26T21:38:37.762ZBud Pollhttp://homeenergypros.lbl.gov/profile/EverettPoll
<p>Let me know when you are done.</p>
<p>Bud</p>
<p>Let me know when you are done.</p>
<p>Bud</p> From Archimedes, On Floating…tag:homeenergypros.lbl.gov,2012-09-26:6069565:Comment:948862012-09-26T19:42:32.017ZRobert Riversonghttp://homeenergypros.lbl.gov/profile/RobertRiversong
<p><b>From Archimedes, On Floating Bodies, Book I:</b></p>
<p>"Any object, wholly or partially immersed in a fluid, is buoyed up by a force equal to the weight of the fluid displaced by the object."</p>
<p>He did not relate this buoyant force to water pressure.</p>
<p> </p>
<p>“<b>Proposition 6:</b> If a solid lighter than a fluid be forcibly immersed in it, the solid will be driven upwards by a force equal to the difference between its weight and the weight of the fluid displaced.”</p>
<p>He…</p>
<p><b>From Archimedes, On Floating Bodies, Book I:</b></p>
<p>"Any object, wholly or partially immersed in a fluid, is buoyed up by a force equal to the weight of the fluid displaced by the object."</p>
<p>He did not relate this buoyant force to water pressure.</p>
<p> </p>
<p>“<b>Proposition 6:</b> If a solid lighter than a fluid be forcibly immersed in it, the solid will be driven upwards by a force equal to the difference between its weight and the weight of the fluid displaced.”</p>
<p>He related the buoyant force only to the differential weight, i.e. the differential result of the force of gravity.</p>
<p> </p>
<p>“<b>Proposition 7:</b> A solid heavier than a fluid will, if placed in it, descend to the bottom of the fluid, and the solid will, when weighed in the fluid, be lighter than its true weight by the weight of the fluid displaced.”</p>
<p>If its density is less than that of the fluid, the apparent weight would be negative. Archimedes, again, defined buoyancy as the difference in the "true weight" and what we today call the "apparent weight" of a submerged object.</p>
<p>Buoyancy is a function of the effective weight, or result of a gravitational field, on an object within a fluid (this is just as true in air as in water).</p>
<p> </p>
<p><b>What is the buoyant force on a block at the bottom of a beaker of water?</b></p>
<p>Carl E. Mungan, Assistant Professor of Physics at the U.S. Naval Academy in Annapolis,</p>
<p>Maryland. <a href="http://www.usna.edu/Users/physics/mungan/Publications/FEd3.pdf" target="_blank">http://www.usna.edu/Users/physics/mungan/Publications/FEd3.pdf</a></p>
<p>"I propose that buoyant force be generally defined as the negative of the total weight of the fluids that are displaced, rather than as the net force exerted by fluid pressures on the surface of an object. In the case of a body fully surrounded by fluids, these two definitions are equivalent. However, if the object makes contact with a solid surface (such as the bottom of a beaker of liquid), only the first, volumetric definition is well defined while the second definition ambiguously depends on how much fluid penetrates between the object and the solid surface."</p> You're also misunderstanding…tag:homeenergypros.lbl.gov,2012-09-26:6069565:Comment:951872012-09-26T18:24:24.698ZRobert Riversonghttp://homeenergypros.lbl.gov/profile/RobertRiversong
<p>You're also misunderstanding your good professor's description. While it's true that it's only the resultant buoyancy vector that is at the center of mass, all buoyancy vectors act in the same direction: up. We use the same center of inertial mass to mathematically describe gravity, even though gravity effects every part of a mass.</p>
<p>But both gravity and buoyancy (the opposite of gravity) operate on all parts of the mass, not on surfaces. The professor contradicted himself when he…</p>
<p>You're also misunderstanding your good professor's description. While it's true that it's only the resultant buoyancy vector that is at the center of mass, all buoyancy vectors act in the same direction: up. We use the same center of inertial mass to mathematically describe gravity, even though gravity effects every part of a mass.</p>
<p>But both gravity and buoyancy (the opposite of gravity) operate on all parts of the mass, not on surfaces. The professor contradicted himself when he acknowledged that buoyancy can also create rotational movement, which depends on the distribution of mass/density <strong>within</strong> the object.</p>
<p>He was straining to explain the buoyancy of a column resting on the bottom of a lake because his (and your) theory don't apply. A more comprehensive explanation is that buoyancy is a relative gravitational effect. A less dense object resting on the bottom of a body of more dense water (which would, obviously, require some form of restraint) will rise when unrestrained because, relative to the surrounding water, gravity has less effect (less "hold") on it.</p>
<p>In other words, buoyancy is to gravity as centrifugal force is to centripetal force: they are mirror images, neither exists without the other, and they are opposite vectors: one down (towards the center) and the other up (away from center).</p> LOLtag:homeenergypros.lbl.gov,2012-09-26:6069565:Comment:951862012-09-26T18:08:14.422ZBud Pollhttp://homeenergypros.lbl.gov/profile/EverettPoll
<p>LOL</p>
<p>LOL</p> Oh, and Dr. Ken Mellendorf's…tag:homeenergypros.lbl.gov,2012-09-26:6069565:Comment:949912012-09-26T17:54:13.613ZRobert Riversonghttp://homeenergypros.lbl.gov/profile/RobertRiversong
<p>Oh, and <font color="#000000" face="Arial, Helvetica, sans-serif">Dr. Ken Mellendorf's language wasn't also just "a convenient shortcut with the wording"? This becomes obvious in his highly strained attempt to explain why the upward buoyancy of a column on the bottom is "caused" by water pressure:</font></p>
<p><font color="#000000" face="Arial, Helvetica, sans-serif"><em><font color="#000000" face="Arial, Helvetica, sans-serif">As for the pillar on the bottom of a lake, there is still water…</font></em></font></p>
<p>Oh, and <font face="Arial, Helvetica, sans-serif" color="#000000">Dr. Ken Mellendorf's language wasn't also just "a convenient shortcut with the wording"? This becomes obvious in his highly strained attempt to explain why the upward buoyancy of a column on the bottom is "caused" by water pressure:</font></p>
<p><font face="Arial, Helvetica, sans-serif" color="#000000"><em><font face="Arial, Helvetica, sans-serif" color="#000000">As for the pillar on the bottom of a lake, there is still water within the material at the bottom. Even a pillar submerged in the sand has water pressing against its bottom. Water also presses on the sand from all sides, which then "transfers" the effect to the bottom of the pillar. Although sand molecules do not exert water pressure in the strictest sense, they do exert a normal force that has the same effect. </font></em><br/></font></p>
<p><font face="Arial, Helvetica, sans-serif" color="#000000">Your problem is that you have latched onto one "convenient shortcut" which gave you some new insight and insist that it's the only "true" description while all the others are wrong.<br/></font></p>
<p><font face="Arial, Helvetica, sans-serif" color="#000000">All of science is mere metaphor to describe in abstract terms what we experience directly in life. And, as in all metaphorically or even "objective" descriptions, the truth of a description depends upon the perspective.<br/></font></p>
<p><font face="Arial, Helvetica, sans-serif" color="#000000"> </font></p>
<p>"When it comes to atoms, language can be used only as in poetry. The poet, too, is not nearly so concerned with describing facts as with creating images..."</p>
<p>- Niels Henrik David Bohr (1885 – 1962) Danish physicist who made foundational contributions to understanding atomic structure and quantum mechanics, for which he received the Nobel Prize in Physics in 1922</p>
<p> </p>
<p>"The outstanding achievement of twentieth century physics is not the theory of relativity with its welding together of space and time, or the theory of quanta with its present apparent negation of the laws of causation, or the dissection of the atom with the resultant discovery that things are not what they seem; it is the general recognition that we are not yet in contact with the ultimate reality. We are still imprisoned in our cave, with our backs to the light, and can only watch the shadows on the wall."</p>
<p>- Sir James Hopwood Jeans (1877 – 1946) English physicist, astronomer and mathematician</p>
<p> </p>
<p>"What we observe is not nature itself, but nature exposed to our method of questioning."</p>
<p>- Werner Karl Heisenberg (1901 – 1976) German theoretical physicist and philosopher who discovered in 1925 a way to formulate quantum mechanics in terms of matrices, for which he was awarded the Nobel Prize for Physics for 1932, and who developed the uncertainty principle in 1927</p>
<p> </p>
<p>"Science is the belief in the ignorance of experts…A great deal more is known than has been proved…Scientific knowledge is a body of statements of varying degrees of certainty – some most unsure, some nearly sure, but none absolutely certain."</p>
<p>- Richard Phillips Feynman (1918 – 1988) American theoretical physicist and Nobel prize recipient for his contribution to quantum electrodynamics, named one of the ten greatest physicists of all time</p>
<p> </p>
<p>"So much of science consists of things we can never see: light 'waves' and charged 'particles'; magnetic 'fields' and gravitational 'forces'; quantum 'jumps' and electron 'orbits.' In fact, none of these phenomena is literally what we say it is…The words we use are merely metaphors."</p>
<p>- K. C. Cole (b. 1946) science writer and professor at USC Annenberg's School of Journalism (described as “the Leonardo da Vinci of science writing”)</p> Robert
Just another example o…tag:homeenergypros.lbl.gov,2012-09-26:6069565:Comment:951842012-09-26T17:12:30.796ZBud Pollhttp://homeenergypros.lbl.gov/profile/EverettPoll
<p>Robert</p>
<p>Just another example of a convenient shortcut with the wording and there are many of them. Another example is your statement "Buoyancy force is a vector force that has only one direction: up. There are no "buoyancy forces pressing in on the sides of a vessel"."</p>
<p>The single vector representation is just the resulting sum of all of the vectors as stated by: <br></br> Dr. Ken Mellendorf <br></br> Physics Instructor <br></br> Illinois Central College</p>
<p>"the center of buoyancy is at…</p>
<p>Robert</p>
<p>Just another example of a convenient shortcut with the wording and there are many of them. Another example is your statement "Buoyancy force is a vector force that has only one direction: up. There are no "buoyancy forces pressing in on the sides of a vessel"."</p>
<p>The single vector representation is just the resulting sum of all of the vectors as stated by: <br/> Dr. Ken Mellendorf <br/> Physics Instructor <br/> Illinois Central College</p>
<p>"the center of buoyancy is at the center of volume because it is essentially the average location. If you add up all the little bits of force on all the little bits of surface area, the effect is the same as applying all these bits of force at the center of volume."</p>
<p><a href="http://www.newton.dep.anl.gov/askasci/phy05/phy05233.htm">http://www.newton.dep.anl.gov/askasci/phy05/phy05233.htm</a></p>
<p>Note, he stated "surface area", as buoyancy forces are applied from the outside, not internally.</p>
<p>There are definitely forces pressing on the all sides of any submerged object. That someone chooses to label the up component of these forces as the buoyancy force does not mean it is the only force being applied.</p>
<p>As for "National Institute for Building Sciences" there is nothing wrong with their labels for their representation per se, it is just without the qualifiers, people like you take them literally and suddenly believe warm air can rise all by itself. Oops, did someone just throw a cup of coffee at me? :) :)</p>
<p>Bud</p> I was doing some unrelated re…tag:homeenergypros.lbl.gov,2012-09-26:6069565:Comment:951832012-09-26T15:50:20.451ZRobert Riversonghttp://homeenergypros.lbl.gov/profile/RobertRiversong
<p>I was doing some unrelated research and stumbled upon this graphic from the National Institute for Building Sciences:</p>
<p><img src="http://www.wbdg.org/images/env_iaq_20.jpg" alt="Stack effect in cold and hot climates" class="noborder" border="0" height="214" width="450"/></p>
<p></p>
<p>I guess they must be confused as well ;-)</p>
<p>I was doing some unrelated research and stumbled upon this graphic from the National Institute for Building Sciences:</p>
<p><img src="http://www.wbdg.org/images/env_iaq_20.jpg" alt="Stack effect in cold and hot climates" class="noborder" border="0" height="214" width="450"/></p>
<p></p>
<p>I guess they must be confused as well ;-)</p>